I want to graph some data in excel. What I have is a number of data points, each with a margin of error. What I want is an xy scatter plot, with vertical whiskers on each point to represent the margin of error. Is there a way to do what I need? Final product should look something like this (the trendline is irrelevant - it should be available, but is beside the point):

Sure. Just use the Stock: High-Low-Close chart. This chart requires those three columns in that order; to convert from value/margin of error, just multiply value * (1+MOE) and (1-MOE), for high and low. You can, of course, format the chart however you want.